Attach a hard control-barrier-function quadratic-program safety filter to a neural policy, but solve the filter with operator splitting and differentiate through its fixed-point map using projection Jacobian-vector products. The network learns the nominal action and task objective end to end, while the deployed action remains the feasible filtered action rather than an unconstrained penalty-based approximation.
Construct a recurrent or state-space layer as a skew product: an expanding bounded feature coordinate drives a linearly contracting hidden state. Constrain the hidden transition matrix A to have spectral radius below one, and monitor the predicted transition ell times the absolute determinant of A equals one: below it, hidden trajectories should occupy a thin or fractal set, while above it they should have substantially higher-dimensional state coverage without losing local contraction.
Train a network to predict the context-dependent observation matrix rather than the latent inverse parameters themselves, then compute the latent parameters with a differentiable ridge-regression solve. This gives one model that can assimilate arbitrary observation vectors, exposes the conditioning of the inverse problem, and avoids forcing an MLP to learn the entire map from observations to parameters.
Parameterize a learned feature-space operator as accretive but not necessarily symmetric, then apply its fractional power through a finite positive mixture of shifted resolvents. This provides a matrix-function layer that can represent directional and rotational interactions while avoiding unstable eigendecomposition of nonnormal matrices.